Apparatus for light-curing a dental object

ABSTRACT

The invention relates to an apparatus for irradiating an object, in particular for light-curing a dental object by means of a first radiation, the apparatus comprising at least one radiation source for emitting the first radiation, the apparatus further comprising at least one radiation sensor for measuring at least a second radiation, and the apparatus further comprising a housing. The second radiation is the first radiation reelected by the object.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims foreign priority benefits under 35 U.S.C.§119(a)-(d) from German patent application ser. no. P 10 2008 031 094.8filed Jul. 1, 2008.

TECHNICAL FIELD

The invention relates to an apparatus for light-curing a dental objectby means of a first radiation, wherein the apparatus is provided with ahousing, at least one radiation source mounted on the housing foremitting the first radiation, and at least one radiation sensor mountedon the housing for measuring at least a second radiation, wherein thesecond radiation is the first radiation reflected by the object.

BACKGROUND OF THE INVENTION

For curing dental filling materials used for the purpose of restorationfor natural teeth but also for separately fabricated sets of teeth,radiation with a high UV portion is employed.

Plastics are popular filling, materials that can be cured withelectromagnetic radiation in material-dependent wavelength ranges(light). A precondition for an optimum polymerization of the plasticmaterial is the introduction of a necessary amount of light, resultingfrom the light power times the exposure time.

When using light the operator precisely has to position the light sourceabove the filling material. If the light is aimed next to the fillingmaterial, not enough light is fed to the filling material. This resultsin not providing the required amount of light in order to cure thefilling material.

Conventional systems have orange filter glasses in order to support thepositioning of the light source, which orange filter glasses subdue thelight in such a manner that the spot is visible, for example in themouth area, on which the light falls. The orange filter glasses,however, are tediously to handle and make the application of the lightsource complicated. Moreover, there are situations in which adetermination of the correct positioning of the light source is notpossible at all.

Modern dental treatment instruments that remove material from the toothby means of a high-energy laser beam are capable of carrying out aposition determination based on the plasma radiation resulting from theremoval of material. In this conjunction, the intensity of the plasmaradiation contains all information about the distance between tooth anddental treatment instrument. Based on this information, the dentaltreatment instrument can be switched off automatically if it ispositioned too far away from the tooth.

When curing filling materials, however, there is no radiation by meansof which it would possible to determine the radiation source.

OBJECTS AND SUMMARY OF THE INVENTION

Therefore, it is the object of the invention to provide an apparatus forirradiating or curing an object, to provide a treatment set forirradiating or curing an object, and to provide a method for irradiationor curing an object, by means of which the position of a radiationsource can be determined more easily.

The invention is based on the concept that for determining the relativeposition of a radiation source with respect to an object, it is notnecessarily required to have a radiation generated by the object. It israther possible to make use of the radiation emitted from the radiationsource and reflected by the object. Surprisingly, it has become apparentthat the radiation of a radiation source when reflected by the object,is changed in a typical manner. This typical change enables a horizontalposition determination of the radiation source since various objects aresituated in the oral area of a patient, for example, that differ fromthe object that is impinged, and that change the radiation of theradiation source in their own typical manner.

In this way, for example, it can easily be checked if the radiationsource is positioned above the filling material that is to be cured.Further, it is possible to determine by means of the run-time of theradiation or by means of the reflected light power measured, how far theradiation source is distant from the object.

According to the invention, a particular apparatus for irradiating anobject by means of a first radiation that has at least one radiationsource, is provided, wherein the radiation source of the apparatus emitsthe first radiation that is reflected by the object as a secondradiation. In this case at least one radiation sensor detects the secondradiation.

By means of detecting the radiation reflected by the object it ispossible to visibly depict the same for the user of the apparatus. Theadvantage is that by means of the apparatus of the present invention itis possible to manually or automatically determine the position of theradiation source. When determining the position manually, on account ofthe radiation measured by the radiation sensor, it is possible for theuser to tell in which way the radiation sensor and thus the apparatusare positioned relative to the object. With the automatic positiondetermination, further improvements are possible, such as an automaticadjustment of the first radiation.

It is particularly expedient to apply the invention in the field ofdental technology. In this case the radiation source irradiates or emitshigh-energy light for curing a dental filling material and is preferablyembodied as a laser or light emitting diode. Most of the dental fillingmaterials are represented brighter than Dentin in the short-wave bluelight range. Therefore, the radiation sensor merely has to determine orascertain whether the radiation that is reflected is very bright. Thisindicates that the radiation source is positioned above the fillingmaterial.

According to the invention it is particularly expedient it the radiationsensor is especially sensitive in a wavelength range that corresponds tothe first radiation emitted from the radiation source. By means of thismeasure, the measuring range can already be limited by these technicalmeans such that the technical realization of the apparatus isparticularly simple.

According to the invention it is especially expedient if the inventiveapparatus is provided with an output device for outputting informationthat is perceptible by the human being. The information can be forexample images, sounds or vibrations. The information is generated basedon the signals that are output by the radiation sensor.

According to the invention is is particularly expedient to detect theintensity of the second radiation. As has already been discussed,radiation with different characteristics is reflected by differentobjects. These characteristics can be the scattering or the degree ofreflection, for example. The inventive apparatus enables to perform theposition determination relative to the object that is irradiated,whereas it is possible to merely evaluate the intensity of the radiationthat is reflected. On the one hand, the intensity directly providesinformation about the characteristics of the object itself since variousobjects reflect the first radiation of the radiation source withdifferent intensities. The intensity, however, can also be taken frominformation on the distance between the radiation source and the object.

According to the invention is particularly favorable to use an outputdevice that distinguishes the perceptible information based on acomparison with at least one reference value. In this case, thereference value is preferably a measured value that has been detected bythe radiation sensor for a predetermined object. By means of theinformation distinguished, such as an optically particularly favorableoutput, a high sound, a vibration or any other distinguishing signaling,an user of the apparatus is immediately able to tell when the apparatusis situated above a desired object such as the tilling material.Therefore, the optimum position of the apparatus can immediately berecognized. Thus, especially for untrained users it is possible to avoidlong initial training time since the apparatus is nearlyself-explanatory.

According to the invention it is particularly expedient to use themeasured values for adjusting the apparatus. In this case, the apparatuscomprises an adjustment device that preferably determines the distancebetween radiation sensor and object based on the second radiation. Basedon this distance the adjustment device can adjust the system parametersof the apparatus. Preferably, those parameters are the emitted lightpower and the on-time of the radiation source. Since the amount of lightof a radiation source that is absorbed by the object, changes more independence on the distance from the object that is irradiated, thisapproach is particularly efficient in the reduction of losses. This notonly saves energy and avoids unnecessary heating of the apparatus, butalso ensures that the amount of light necessary to effectpolymerization, is supplied to the object.

According to the invention it is particularly expedient to have amultiple arrangement of the radiation sensors. When curing a toothfilling material, the multiple arrangement can be embodied in hood shapein order to detect the irradiation of the filling material. In case theradiation sensor is received in such a multiple arrangement, theinvention is particularly efficient since a hood-shaped multiplearrangement of light sources mostly blocks the unhindered sight or clearview of the object that is to be treated.

In a further advantageous embodiment it is provided that a radiationsource is preferably formed by at least one laser diode or lightemitting diode, whereas each light emitting diode at least comprises oneLED-chip.

In a further advantageous embodiment it is provided that the radiationsource and the at least one radiation sensor are arranged at the housingor are part of an attachment that is detachably mounted on the housing.

In a further advantageous embodiment it is provided that the radiationsource emits a first radiation with a wavelength of 320 nm to 750 nm.

In a further advantageous embodiment it is provided that the radiationsensor is sensitive in a wavelength range of the first radiation emittedby the radiation source.

In a further advantageous embodiment it is provided that at least one ofthe radiation sensors is an image sensor by means of which at least onepicture of the object can be taken.

In a further advantageous embodiment it is provided that one second or aplurality of radiation sensors are provided that are arranged in spacedapart relationship in the same plane and/or in angles relative to theradiation sensor.

In a further advantageous embodiment it is provided that the apparatuscomprises an output device for outputting perceptible information.

In a further advantageous embodiment it is provided that the perceptibleinformation is based on at least one measured value from at least oneradiation sensor, the measured value in particular indicating theintensity of the second radiation or being compared to at least onreference value.

In a further advantageous embodiment it is provided that the outputdevice is embodied as a display that is arranged at the apparatus and/orthe output device outputs the information in a visual and/or acousticaland/or sensible manner.

In a further advantageous embodiment it is provided that the apparatusdetermines the distance to the reflection surface from the secondradiation.

In a yet further advantageous embodiment there is provided an apparatusfor indicating the radiation that is measured by at least one radiationsensor.

In a further advantageous embodiment it is provided that a chargingstation for charging and/or storing the apparatus is provided.

In a further advantageous embodiment the following steps are provided:irradiating the dental object by means of a radiation source; measuringthe reflected radiation; and detecting a reflected radiation; anddetecting a relative position of the radiation source with respect tothe dental object based on the reflected light.

BRIEF DESCRIPTION OF THE FIGURES

Further advantages, details and features will become apparent from thefollowing description of exemplary embodiments of the invention withreference to the drawings, in which:

FIG. 1 shows a diagrammatic view of a first exemplary embodiment of theinvention;

FIG. 2 shows a diagrammatic view of a second exemplary embodiment of theinvention that comprises a charging station;

FIG. 3 shows a diagrammatic view of a third exemplary embodiment of theinvention having hood shape;

FIG. 4 shows a diagrammatic view of a fourth exemplary embodiment of theinvention having U-shape in cross section, FIG. I-II being a sectionalview taken along the line I-II in FIG. 4.

FIG. 5 shows a diagrammatic view of a fifth exemplary embodiment of theinvention having arc shape.

DETAILED DESCRIPTION

As previously noted, it is a feature of this invention to provide anapparatus for irradiating an object by means of a first radiation from aradiation source, wherein the first radiation that is reflected by theobject is a second radiation, the apparatus being provided with a sensorfor detect the second radiation. The inventive apparatus and the objectthat is to be irradiated are embodied as a polymerization lamp and as adental filling material in all preferred embodiments. The material ofthe filling is plastic material and soft at first. The plastic materialused for the restoration process is cured by means of radiation that isa high-energy radiation with a comparably large spectral blue portion inthe present embodiment.

FIG. 1 shows a polymerization lamp 100 having a radiation source 110 anda radiation sensor 120.

The radiation source 110 is a light-emitting diode, in short LED 110 inall embodiments. However, this is not to be understood in a limitingsense, since also other suitable radiation sources such as halogenlamps, xenon lamps and laser diodes are known to a person skilled in theart. In operation, the LED 110 emits light with a high portion of bluelight, by means of which the plastic material is irradiated and cured.The efficiency and through-curing of the filling material with the aidof the LED 110 depends crucially on the skill of the user. If the userexactly hits the plastic filling material with the light beam, the LED110 has to emit less energy for the complete curing process than in thecase that the user takes aim at the filling somewhat off-center. Aspecific problem is that in this case no information is available on thefact how much radiation energy the filling was exposed to. For example,a sufficient light power may be applied to portions of the filling,whereas other portions are not. The user up to now was not able torecognize, how far the filling had already cured. Finally an incorrectrating lead to an incompletely cured tooth filling.

In order to avoid the problems mentioned, according to the invention,the radiation sensor 120 is incorporated into the polymerization lamp100 such that it is oriented into the same direction than the LED 110.Thus, the radiation sensor absorbs the light that is reflected by thefilling and generates a signal based on the properties of the reflectedlight.

This signal can be used as information for the user. Preferably thesignal of the radiation sensor 120 is used for determining the position.

In a first embodiment the radiation sensor 120 is embodied as a camera120. The pictures taken by the camera 120 can be depicted on a display130. This opens at first the possibility for the dentist or other usersto make sure with a short glance on the display, if necessary, how therestoration result is represented optically, and even during the curingprocess. An experienced dentist typically recognizes the polymerizationand can already determine by means of a short visual judgement, how farpolymerization has progressed.

According to the invention it is particularly expedient in thisconjunction that it is not necessary to insert an orange filter suchthat the full light power and the full spectrum are available for thejudgement.

Instead of a charge coupled device (CCD) unit, the radiation sensor 120can also simply be embodied as a photo-sensitive transistor. In thiscase the reflected light radiation strikes the transistor and increasesor decreases the resistance of the transistor. The intensity of thereflected radiation thus influences the resistance of thephototransistor whose output signal is evaluated. With this solution itcan be taken advantage of the fact that plastic material as fillingmaterial reflects light with a large portion of blue light with a higherintensity than the tooth itself that is to be restored. With aNPN-phototransistor, the light reflected by the filling material wouldproduce a lower resistance than the light that is reflected by the toothitself. The phototransistor can be interconnected in a measuring bridgefor example, and by means of a corresponding evaluation circuit it canbe assessed whether and to what extent the restoration material that isto be cured is impinged by the first radiation from the radiation source110.

Also the camera 120 can easily be used for the assessment of theintensity of the reflected light radiation. The portions of the fillingmaterial that are impinged by the first radiation reflect the lightradiation stronger such that brighter image areas are represented thereby the camera 120. These brighter image areas can not only be depictedon a display but can also be evaluated by means of a correspondingevaluation circuit, in order to determine whether and to what extent thefilling material is impinged by the first radiation.

In an alternative embodiment of the invention, the light radiationreflected by the object is evaluated and is compared to a first and asecond reference value. If the light radiation that has been evaluatedexceeds the first reference value, a signaling occurs that the positionof the light curing apparatus has been correctly selected. If the lightradiation reflected is below the first reference value or is above thesecond reference value, a suitable warning is generated, for example onthe display 130, in order to inform the dentist that corresponding errorconditions are present. A corresponding warning signal can be outputacoustically.

In this case, the distance from the surface of the restoration materialcan be determined by performing a visual judgement on the display.Alternatively, the distance can be determined from the absolute quantityof the second radiation, since the intensity of the reflected radiationdecreases with increasing distance from the surface that is impinged.

Alternatively or additionally, the radiation sensor 120 can also be usedfor determining the distance between polymerization lamp 100 andradiation sensor 120.

Preferably the radiation sensor 120 comprises a spectral sensitivitythat forms a large overlap with the emission wavelength range of the LED110. Thus, the necessity for employing filters is removed.

In a further preferred embodiment several radiation sensors 120 that arearranged in angles relative to one another, can be incorporated whichare provided for determining the position and/or distance.

As discussed above, the apparatus comprises an adjustment device thatpreferably determines the distance between radiation sensor and objectbased on the second radiation. Based on this distance the adjustmentdevice can adjust the system parameters of the apparatus. Preferably,those parameters are the emitted light power and the on-time of theradiation source. Since the amount of light of a radiation source thatis absorbed by the object, changes more in dependence on the distancefrom the object that is irradiated, this approach is particularlyefficient in the reduction of losses. This not only saves energy andavoids unnecessary heating of the apparatus, but also ensures that theamount of light necessary to effect polymerization, is supplied to theobject.

FIG. 2 shows a polymerization lamp 310 according to a second exemplaryembodiment of the invention. Also in the second exemplary embodiment allfunctional features of the first exemplary embodiment can be integratedin the polymerization lamp 310. Thus the lamp 310 is provided with aradiation source 110 and a radiation sensor 120.

Further, the polymerization lamp 310 is accommodated in a chargingdevice 330, which is provided with a display 130. This charging device330 can be provided for charging a storage battery (not shown) of thepolymerization lamp 310. In this case, the charging device 330 comprisesa power supply 340 in the form of a plug that can be inserted or pluggedinto a plug receptacle of the public power supply network. Moreover, thecharging device 330 also needs corresponding transformers in order toconvert the voltage from the power supply network in a suitable chargingvoltage for the storage battery.

Further, the charging device 330 may also comprise a display 320 that issuitable for representing the position data and distance data that havebeen detected. These data can also be stored on a storage means (notshown) in the charging device 330.

FIG. 3 shows a multiple-sensor arrangement for the polymerization lampaccording to a third exemplary embodiment of the invention. Accordingly,the LED 110 and the camera 120 are incorporated topside in the dome of ahood 400 that can be held above a natural or artificial tooth that is tobe treated. The advantage of a hood of this kind is that the light fromthe LED 110 can be reflected from the walls of the hood in order to useit more efficiently for curing the filling material that is insertedinto the tooth.

When using the hood 400, the sight of the filling material is coveredduring the curing process. By means of using the invention, however, itis now possible to effect the correct positioning and the correctdistance between the LEDs 110, the hood and the filling material. Inthis respect, by means of the inventive position determination in thisembodiment, by using the hood 400 the particular advantage can beachieved that an exactly defined and high-energy light radiation issupplied to the filling material at an exactly prescribed position.

In a further development of the hood 400 it comprises further cameras410, 420, 430 at its inner edge. Those are substantially perpendicularto the camera 120 that is situated topside in the hood 400.

This arrangement of the cameras 410 to 430 enables the determination ofthe exact position of the hood 400 before switching on the radiationsource 110. Thus, a visual judgement of the dental restoration is alsopossible, and the relative positioning and the visual configuration ofthe current situation can be represented in clearly enlarged form and isthus clearly apparent on the display.

FIG. 4 shows a modified multiple arrangement of sensors and radiationsources for a polymerization lamp according to a fourth exemplaryembodiment of the invention. In this embodiment at least one LED 110 andone camera 120 are installed in the top area of a hood 500, wherein theconfiguration of the hood 500 substantially corresponds to a verticallyoriented U-shape and in this respect can be randomly positioned along aset of teeth. Preferably, the hood 500 comprises a plurality of LEDs 110and cameras 120, wherein a pair of a LED 110 and a camera 120 can bepositioned above a tooth.

Further cameras 510, 520 can be arranged at the inner edge of a dentalarch shaped trough substantially perpendicular to the further cameras120. This becomes apparent from the sectional representation I-II.

In a further modified embodiment according to FIG. 5 a particularlyformed multiple arrangement of LEDs 110 and sensors 120 are positionedat the center of a U-shaped hood 600. Additional camera 610, 620 arepositioned at the edge. In this embodiment, the overall shape is formedsuch that it completely covers a dental set of natural or artificialteeth, and actually pretty tight, wherein the hood shape in thesectional view substantially extends semicircular over the pertainingtooth. In this conjunction, a plurality of light sources and sensors aremounted in random and suitable manner, and the light power emittedprovides a uniform and bright illumination of the entire set of teeth.

While a preferred form of this invention has been described above andshown in the accompanying drawings, it should be understood thatapplicant does not intend to be limited to the particular detailsdescribed above and illustrated in the accompanying drawings, butintends to be limited only to the scope of the invention as defined bythe following claims. In this regard, the term “means for” as used inthe claims is intended to include not only the designs illustrated inthe drawings of this application and the equivalent designs discussed inthe text, but it is also intended to cover other equivalents now knownto those skilled in the art, or those equivalents which may become knownto those skilled in the art in the future.

1. Apparatus for light-curing a dental object by means of a firstradiation, the apparatus comprising: a housing; at least one radiationsource mounted on the housing for emitting the first radiation; at leastone radiation sensor mounted on the housing for measuring at least asecond radiation, wherein the second radiation is the first radiationreflected by the object.
 2. Apparatus as claimed in claim 1, wherein theradiation source is preferably formed by at least one laser diode orlight-emitting diode LED, each LED having at least one LED-chip. 3.Apparatus as claimed in claim 1, wherein the radiation source emits afirst radiation having a wavelength of 320 nm to 750 nm.
 4. Apparatus asclaimed in claim 1, wherein the radiation sensor is sensitive in awavelength range of the first radiation emitted by the radiation source.5. Apparatus as claimed in claim 1, wherein at least one of theradiation sensors is an image sensor, by means of which at least onepicture of the object can be taken.
 6. Apparatus as claimed in claim 1,wherein one radiation sensor is centrally located, and a plurality ofother radiation sensors are provided that are arranged in spaced apartrelationship in the same plane and/or in angles relative to the oneradiation sensor.
 7. Apparatus as claimed in claim 1, wherein theapparatus comprises an output device for outputting perceptibleinformation.
 8. Apparatus as claimed in claim 7, wherein the perceptibleinformation is based on at least one measured value from at least oneradiation sensor, the measured value in particular indicating theintensity of the second radiation or being compared to at least onereference value.
 9. Apparatus as claimed in claim 7, wherein the outputdevice is embodied as a display that is arranged on the apparatus,and/or the output device outputs the information in a visual and/oracoustical and/or sensible manner.
 10. Apparatus as claimed in claim 1,wherein the apparatus determines the distance to the reflection surfacefrom the second radiation.
 11. Method for curing an object, the methodbeing characterized by the following steps: irradiating the dentalobject with a radiation source; measuring the radiation that isreflected; and detecting a radiation that is reflected; and detecting arelative position of the radiation source with respect to to the dentalobject based on the reflected light.